Saving energy, improving energy efficiency of energy consumption and reducing greenhouse gas (GHG) emissions are key initiatives in many cities and municipalities and for building owners and operators. Inventors in this disclosure have recognized that in order to reduce energy consumption in buildings, one should understand patterns of energy usage, characteristics of building structures, operations and occupant behaviors that influence energy consumption. However, building structures often have different characteristics, for instance, each being built with unique or different characteristics and designs from one another. Due to such heterogeneity in buildings, improvements that can be made to buildings to save energy and their effectiveness can be very different for different buildings.
One way to reduce energy consumption is to retrofit buildings to improve the energy efficiency. Examples of retrofit include window replacement, e.g., from single glazing to double glazing; adding insulation to roof, wall or ground slab; replacing boilers; installing window shading; replacing boiler insulation; roof coloring, and others. Each retrofit involves cost, but mostly likely will save certain amount of energy and its costs, mostly likely will also reduce GHG emission, and may realize return of investment in a few years (known as payback periods). Building portfolio owners (e.g., cities, municipalities, schools, etc.) usually have a limited amount of budget to spend for retrofit. When there are multiple buildings involved, it is not easy to decide which retrofit for which building should be selected within the limited budget and which would provide the more of the benefits. Therefore, the inventors in this application have recognized that it would be helpful to understand what would be an optimal retrofitting plan, for example, which buildings should be retrofitted, what would be type of retrofit, and what return on investment (ROI) would be realized, with the limited budget and goals of energy reduction, energy cost reduction and GHG emission.